This invention relates to a conveyor pan assembly for an armored face conveyor, such as for handling coal in a longwall face mining system.
A variety of different apparatuses exist for mining coal and other materials from underground seams. One apparatus is a continuous mining machine used in instances where extended portions or longwalls of seam are mined. Such longwalls may, depending upon the seam configuration, extend for distances of 300-1200 or more feet. It is standard practice in this type of mining to mine parallel entries into the seam to be mined and connect those entries with one or more primary passages. Such arrangement defines the longwall faces to be mined. The roof of the primary passages are usually supported by movable roof supports during the mining of the exposed “face” of the longwall pillar.
Conventional longwall mining techniques employ a mining machine that is known in the industry as a longwall shearer. A longwall shearer typically has an elongated mobile frame that is supported on powered roof supports that are adjacent and substantially parallel to the mine face. Rotary driven toothed drums are operably supported on arms on each end of the elongated frame for winning the coal as the frame passes back and forth before the mine face. The won material falls into a face conveyor that is usually attached to the floor-mounted tracks and extends parallel to the longwall face. The face conveyor discharges the material onto other conveying apparatuses to transport the material from the seam. As the mine face recedes, the conveyor and track assembly is advanced forward to enable the shearer to continue mining.
Typically, the face conveyor includes a plurality of conveyor pans, and each conveyor pan includes a hardened steel deck plate secured to supporting cast steel side members or rails. The plurality of conveyor pans is assembled in end-to-end relationship to form a complete conveyor system for moving coal or other mineral along and away from the mine face under active excavation.
The pan assembly side members additionally support the haulage system for the shearer. A scraper chain extends along the entire conveyor system length with spaced flights serving to move the coal along the deck plate. The strength of the armored face mining conveyor and its structural integrity is of a primary concern. Eliminating structural failures in the conveyor system, and thus minimizing down time, is important to assure an efficient longwall mining operation.
The operating environment of a mine is extremely harsh on mechanical equipment of all forms. The very nature of the work objective is to cut and remove abrasive material. Moreover, the abrasive material is fluidized in the presence of water and contaminated oil. In the case of material removal conveyors, the abrasive aggregate is wiped along the conveyor pan surfaces to exacerbate the grinding destruction. In addition to the abrasive and corrosive nature of the environment, the machinery is subjected to extreme ranges of shock, mechanical twisting, racking and concentrated stresses due to uneven support surfaces.
The pan assembly side members of known conveyors have right angle ends with a single chamfer, or are formed to make a mating scarf joint.